1. Field of the Invention
The present invention relates to an automatic level control circuit which adjusts the signal level of an analog audio signal.
2. Description of the Related Art
Apparatuses such as TVs, car audio systems, home theater systems, and audio components, which output sound (audio signals) have a function for automatically controlling the volume of the audio signal (ALC: Automatic Level Control) so as to allow listeners/viewers to easily listen to the audio. ALC allows the level of a quiet sound to be raised, and allows the level of a loud sound to be reduced, in a case in which the dynamic range of the audio signal is very large. Also, ALC is effective in a case in which there is a great difference in volume between television programs and commercials.
In general, such an ALC circuit has a configuration including a variable gain amplifier configured to amplify an audio signal and a control unit configured to monitor the level (amplitude) of the audio signal input to the variable gain amplifier, and to control the gain of the variable gain amplifier according to the level thus monitored.